package unit;

import java.util.*;

/**
 * SpringFrameworkTest — CWE-407 benchmark for spring-framework defects.
 *
 * spring-framework-0001: CorsConfiguration.checkHeaders() O(R×A)
 *   checkHeaders() does a nested loop: for each of R request headers,
 *   it scans A allowedHeaders via equalsIgnoreCase(). Total O(R×A).
 *   Fix: build a case-insensitive Set<String> once O(A), then O(1) lookup
 *   per request header → O(R+A) total.
 *
 * spring-framework-0002: AcceptHeaderLocaleResolver.findSupportedLocale() O(R×S)
 *   For each of R Accept-Language locales, calls supportedLocales.contains(locale)
 *   on an ArrayList — O(S) linear scan. Total O(R×S) per request.
 *   Same defect in AcceptHeaderLocaleContextResolver (reactive).
 *   Fix: use LinkedHashSet for O(1) full-locale match → O(R+S) total.
 *
 * spring-framework-0003: EncodedResourceResolver.contentCodings ArrayList O(A×C)
 *   resolveResourceInternal() iterates acceptedCodings from the request header,
 *   calling this.contentCodings.contains(acceptedCoding) on an ArrayList → O(C)
 *   per accepted coding. Total O(A×C) per static resource request.
 *   Fix: change contentCodings to LinkedHashSet → O(1) contains → O(A) total.
 */
public class SpringFrameworkTest {

    // -----------------------------------------------------------------------
    // spring-framework-0001: CorsConfiguration.checkHeaders O(R×A)
    // -----------------------------------------------------------------------

    /** Unpatched: inner for-loop scan of allowedHeaders for each request header. */
    static long checkHeadersUnpatched(int numRequestHeaders, int numAllowedHeaders) {
        List<String> requestHeaders = new ArrayList<>(numRequestHeaders);
        for (int i = 0; i < numRequestHeaders; i++) requestHeaders.add("x-custom-req-" + i);

        List<String> allowedHeaders = new ArrayList<>(numAllowedHeaders);
        for (int i = 0; i < numAllowedHeaders; i++) allowedHeaders.add("x-allowed-" + i);

        long ops = 0;
        List<String> result = new ArrayList<>();
        for (String requestHeader : requestHeaders) {
            for (String allowedHeader : allowedHeaders) {
                ops++;  // equalsIgnoreCase probe
                if (requestHeader.equalsIgnoreCase(allowedHeader)) {
                    result.add(requestHeader);
                    break;
                }
            }
        }
        return ops;
    }

    /** Patched: build lowercase Set once, O(1) lookup per request header. */
    static long checkHeadersPatched(int numRequestHeaders, int numAllowedHeaders) {
        List<String> requestHeaders = new ArrayList<>(numRequestHeaders);
        for (int i = 0; i < numRequestHeaders; i++) requestHeaders.add("x-custom-req-" + i);

        List<String> allowedHeaders = new ArrayList<>(numAllowedHeaders);
        for (int i = 0; i < numAllowedHeaders; i++) allowedHeaders.add("x-allowed-" + i);

        long ops = 0;
        Set<String> allowedSet = new LinkedHashSet<>(numAllowedHeaders * 2);
        for (String h : allowedHeaders) {
            allowedSet.add(h.toLowerCase(Locale.ROOT));
            ops++;  // set build: O(A)
        }

        List<String> result = new ArrayList<>();
        for (String requestHeader : requestHeaders) {
            ops++;  // O(1) hash lookup
            if (allowedSet.contains(requestHeader.toLowerCase(Locale.ROOT))) {
                result.add(requestHeader);
            }
        }
        return ops;
    }

    // -----------------------------------------------------------------------
    // spring-framework-0002: AcceptHeaderLocaleResolver O(R×S)
    // -----------------------------------------------------------------------

    /**
     * Unpatched: ArrayList.contains() = O(S) linear scan per request locale.
     * Tests the primary hot path: full-locale exact match via contains().
     * Uses country-code locales so there is no language-only fallback hit.
     */
    static long resolveLocaleUnpatched(int numRequestLocales, int numSupportedLocales) {
        // Request locales: zh-XX0, zh-XX1, ... (no match with supported set)
        List<Locale> requestLocales = new ArrayList<>(numRequestLocales);
        for (int i = 0; i < numRequestLocales; i++) {
            requestLocales.add(new Locale("zh", "XX" + i));
        }

        // Supported locales: en-ZZ0, en-ZZ1, ... (different language, no overlap)
        List<Locale> supportedLocales = new ArrayList<>(numSupportedLocales);
        for (int i = 0; i < numSupportedLocales; i++) {
            supportedLocales.add(new Locale("en", "ZZ" + i));
        }

        long ops = 0;
        for (Locale locale : requestLocales) {
            // Simulates ArrayList.contains(locale) — O(S) scan (no early exit, no match)
            for (Locale s : supportedLocales) {
                ops++;
                if (s.equals(locale)) break;
            }
        }
        return ops;
    }

    /**
     * Patched: LinkedHashSet.contains() = O(1) per request locale.
     * Build the set once O(S), then O(1) per request locale.
     */
    static long resolveLocalePatched(int numRequestLocales, int numSupportedLocales) {
        List<Locale> requestLocales = new ArrayList<>(numRequestLocales);
        for (int i = 0; i < numRequestLocales; i++) {
            requestLocales.add(new Locale("zh", "XX" + i));
        }

        List<Locale> supportedLocalesList = new ArrayList<>(numSupportedLocales);
        for (int i = 0; i < numSupportedLocales; i++) {
            supportedLocalesList.add(new Locale("en", "ZZ" + i));
        }

        long ops = 0;
        // Build set once — O(S)
        Set<Locale> supportedSet = new LinkedHashSet<>(supportedLocalesList);
        ops += numSupportedLocales;

        for (Locale locale : requestLocales) {
            ops++;  // O(1) set lookup
            boolean found = supportedSet.contains(locale);
        }
        return ops;
    }

    // -----------------------------------------------------------------------
    // spring-framework-0003: EncodedResourceResolver.contentCodings O(A×C)
    // -----------------------------------------------------------------------

    /** Unpatched: ArrayList.contains() = O(C) scan per accepted-encoding token. */
    static long encodedResolverUnpatched(int numAcceptedCodings, int numContentCodings) {
        List<String> acceptedCodings = new ArrayList<>(numAcceptedCodings);
        for (int i = 0; i < numAcceptedCodings; i++) acceptedCodings.add("enc-acc-" + i);

        List<String> contentCodings = new ArrayList<>(numContentCodings);
        for (int i = 0; i < numContentCodings; i++) contentCodings.add("enc-cfg-" + i);

        long ops = 0;
        for (String accepted : acceptedCodings) {
            // Simulates ArrayList.contains(accepted) — O(C) scan
            for (String supported : contentCodings) {
                ops++;
                if (supported.equals(accepted)) break;
            }
        }
        return ops;
    }

    /** Patched: LinkedHashSet.contains() = O(1) per accepted-encoding token. */
    static long encodedResolverPatched(int numAcceptedCodings, int numContentCodings) {
        List<String> acceptedCodings = new ArrayList<>(numAcceptedCodings);
        for (int i = 0; i < numAcceptedCodings; i++) acceptedCodings.add("enc-acc-" + i);

        Set<String> contentCodings = new LinkedHashSet<>(numContentCodings * 2);
        for (int i = 0; i < numContentCodings; i++) contentCodings.add("enc-cfg-" + i);

        long ops = 0;
        for (String accepted : acceptedCodings) {
            ops++;  // O(1) hash lookup
            boolean found = contentCodings.contains(accepted);
        }
        return ops;
    }

    // -----------------------------------------------------------------------
    // main
    // -----------------------------------------------------------------------

    public static void main(String[] args) {
        int pass = 0, total = 0;

        // spring-framework-0001: R=20, A=50 — worst case no match (all custom headers differ)
        {
            total++;
            int R = 20, A = 50;
            long slow = checkHeadersUnpatched(R, A);
            long fast = checkHeadersPatched(R, A);
            double ratio = (double) slow / Math.max(fast, 1);
            boolean ok = ratio > 10.0 && slow >= (long) R * A;
            if (ok) pass++;
            System.out.printf("  %s spring-framework-0001: checkHeaders ArrayList O(R×A) → Set O(R+A)"
                    + "  R=%d A=%d  slow=%,d fast=%,d  ratio=%.0fx%n",
                    ok ? "PASS" : "FAIL", R, A, slow, fast, ratio);
            if (!ok) {
                System.err.printf("  FAIL spring-framework-0001: expected ratio>10x and slow>=%d, got ratio=%.1f slow=%d%n",
                        (long) R * A, ratio, slow);
            }
        }

        // spring-framework-0002: R=15, S=20 — worst case no match
        {
            total++;
            int R = 15, S = 20;
            long slow = resolveLocaleUnpatched(R, S);
            long fast = resolveLocalePatched(R, S);
            double ratio = (double) slow / Math.max(fast, 1);
            // Unpatched worst case: R×S full scans; patched: S+R ops
            boolean ok = ratio > 5.0 && slow >= (long) R * S;
            if (ok) pass++;
            System.out.printf("  %s spring-framework-0002: localeResolver ArrayList O(R×S) → Set O(R+S)"
                    + "  R=%d S=%d  slow=%,d fast=%,d  ratio=%.0fx%n",
                    ok ? "PASS" : "FAIL", R, S, slow, fast, ratio);
            if (!ok) {
                System.err.printf("  FAIL spring-framework-0002: expected ratio>5x and slow>=%d, got ratio=%.1f slow=%d%n",
                        (long) R * S, ratio, slow);
            }
        }

        // spring-framework-0003: A=10 accepted codings (exaggerated), C=8 configured codings
        {
            total++;
            int A = 10, C = 8;
            long slow = encodedResolverUnpatched(A, C);
            long fast = encodedResolverPatched(A, C);
            double ratio = (double) slow / Math.max(fast, 1);
            // Unpatched worst case: A×C; patched: A ops
            boolean ok = ratio > 3.0 && slow >= (long) A * C;
            if (ok) pass++;
            System.out.printf("  %s spring-framework-0003: encodedResolver ArrayList O(A×C) → Set O(A)"
                    + "  A=%d C=%d  slow=%,d fast=%,d  ratio=%.0fx%n",
                    ok ? "PASS" : "FAIL", A, C, slow, fast, ratio);
            if (!ok) {
                System.err.printf("  FAIL spring-framework-0003: expected ratio>3x and slow>=%d, got ratio=%.1f slow=%d%n",
                        (long) A * C, ratio, slow);
            }
        }

        System.out.println();
        System.out.printf("%d/%d PASS%n", pass, total);

        if (pass < total) {
            System.out.println("FAIL");
            System.exit(1);
        }

        System.out.println("ALL PASS");
    }
}